RT Journal Article
SR Electronic
T1 Atomic-scale compositional mapping reveals Mg-rich amorphous calcium phosphate in human dental enamel
JF Science Advances
JO Sci Adv
FD American Association for the Advancement of Science
SP e1601145
DO 10.1126/sciadv.1601145
VO 2
IS 9
A1 La Fontaine, Alexandre
A1 Zavgorodniy, Alexander
A1 Liu, Howgwei
A1 Zheng, Rongkun
A1 Swain, Michael
A1 Cairney, Julie
YR 2016
UL http://advances.sciencemag.org/content/2/9/e1601145.abstract
AB Human dental enamel, the hardest tissue in the body, plays a vital role in protecting teeth from wear as a result of daily grinding and chewing as well as from chemical attack. It is well established that the mechanical strength and fatigue resistance of dental enamel are derived from its hierarchical structure, which consists of periodically arranged bundles of hydroxyapatite (HAP) nanowires. However, we do not yet have a full understanding of the in vivo HAP crystallization process that leads to this structure. Mg2+ ions, which are present in many biological systems, regulate HAP crystallization by stabilizing its precursor, amorphous calcium phosphate (ACP), but their atomic-scale distribution within HAP is unknown. We use atom probe tomography to provide the first direct observations of an intergranular Mg-rich ACP phase between the HAP nanowires in mature human dental enamel. We also observe Mg-rich elongated precipitates and pockets of organic material among the HAP nanowires. These observations support the postclassical theory of amelogenesis (that is, enamel formation) and suggest that decay occurs via dissolution of the intergranular phase. This information is also useful for the development of more accurate models to describe the mechanical behavior of teeth.